In the last week, we have two major data points that suggest the city’s labor movement — while large and collectively powerful — is simply too diverse, and maybe too disjointed, to pull off a power play like picking a mayor for the rest of us.

• First, Henry Nicholas, president of the National Union of Hospital & Health Care Employees Local 1199, broke from the pack and made his own endorsement in the mayor’s race: Councilman Jim Kenney. He then basically invited John Dougherty, AKA “Johnny Doc,” AKA “the politically powerful business manager of the IBEW Local 98,” to rubber stamp his decision and take City Hall together: “Johnny’s got the money and I’ve got the troops,” Nicholas said.

Dougherty never responded publicly. Behind the scenes, too, observers cast doubt on whether he would sign on to Nicholas’s endorsement.

It wasn’t just Dougherty who crossed the line, to be fair. It was his union, IBEW Local 98, as well Laborers Local 332 and Stagehands Local 8 — the groups that last week signed a contract which freed the Convention Center from sclerotic work rules that had apparently driven off a number of potential customers.

Carpenters Local 8 and the Teamsters Local 107 didn’t sign by the deadline, were shut out of the process, and this week picketed the Convention Center. Dougherty escorted his workers right past the signs, leaving Teamsters leader William Hamilton spluttering. “I believe it’s reprehensible that John Dougherty would show up in a picket line today and cross a union picket line,” he said. “I think it sets the union movement in Philadelphia back a hundred years.”

Now: Let’s dispense with ideas of who is right and who is wrong in this kerfuffle. For our purposes it really doesn’t matter.

The more important point is this: The one thing that unions are supposed to be really good at — supporting each other when time comes to confront the boss — is the one thing they’ve steadfastly refused to do in Philadelphia this week. There’s a reason a billion-and-one labor ballads feature the word “solidarity”: Without it, the leverage of unions is pretty much nil.

That leads an observer to ask: If the city’s labor unions can’t even show solidarity on a job site — the whole reason they exist — what’s the likelihood they’ll stick together on a political campaign?

The answer is: They probably don’t. IBEW has its interests; the Teamsters have theirs. Sometimes the twain shall meet, but not always.

The good news? There’s less chance now for one candidate to pick up a home run mayoral endorsement from all the unions and thus drive all the competitors out before the race really begins. The trouble among the unions makes it more likely we’ll see a real campaign with multiple candidates, concluding with voters making a decision at the polls instead of colorful characters anointing their pick in a backroom.

“It’s not a matter of if we’re going to be all together,” Johnny Doc said back in February. “It’s a matter of who we’re going to be all together behind.” Turns out, both questions are still very much open.